Analytical Transmission Electron Microscopy: An Introduction for Operators

ISBN-13: 9789401779883 / Angielski / Miękka / 2016 / 348 str.

Jurgen Thomas; Thomas Gemming

Opis

Based on the authors' years of experience as instructors, this book is an introduction for all persons who want to use a transmission electron microscope. Offers illustrative examples, simple models and practical hints on analytical transmission microscopy.

Spis treści

1. Why such an effort?.- The problem with the magnification.- The limitation of resolution.- Electron waves.- The role of magnification.- 2. What should we know about electron optics and the construction of an electron microscope.- The principle of multistage imaging.- Rotational-symmetric magnetic fields as electron lenses.- Lens aberrations.- Resolution limit considering the spherical aberration.- Electron gun.- “Richtstrahlwert” (brightness).- We construct an electron microscope.- Illumination system.- Imaging system.- Specimen stage.- Acquiring the images.- Vacuum system.- Miscellaneous.- We prepare electron-transparent samples.- What is the challenge?.- “Classical” methods.- Cutting, grinding, and ion milling.- Focused Ion Beam (“FIB”) techniques.- 4. Let us start with practical microscopy.- What do we peripherally need?.- We put the specimen into the holder and insert it into the microscope.- We check the (alignment) state of the microscope.- Focussing the image – sharpness and contrast.- Contamination and sample damaging.- 5. Let us switch to electron diffraction.- Why diffraction reflexes?.- Crystal lattices and lattice planes.- Selected area and convergent beam electron diffraction.- What can we learn from selected area diffraction patterns?.- Radii in ring diagrams.- Rules for forbidden reflections.- Intensities of diffraction reflections.- Positions of diffraction reflections in point diagrams.- Indexing of diffraction reflections.- Kikuchi- and HOLZ-lines.- Amorphous samples.- 6. Why do we see any contrast in the images?.- Elastic scattering of electrons within the sample.- Mass thickness and diffraction contrast.- Brightfield and darkfield imaging.- Bending contours, dislocations, and semicoherent particles.- Thickness contours, stacking faults, and twins.- Moiré patterns.- Magnetic domains: Lorentz microscopy.- 7. We increase the magnification.- Imaging of atomic columns in crystals: Phase contrast.- Contrast transfer by the objective lens.- Wave-optical interpretation of the resolution limit.- Periodic distribution of brightness in pictures: Fourier analysis.- Mass thickness and phase contrast.- Contrast of amorphous samples.- Correction of astigmatism.- Measurement of the resolution limit.- Correction of spherical and chromatic aberration.- Interpretation of high resolution TEM images.- 8. Let us switch to scanning transmission electron microscopy.- What happens electron-optically?.- Resolution or: What is the smallest diameter of the electron probe?.- Contrast in the scanning transmission electron microscopic image.- Speciality: High angle annular darkfield detector (HAADF).- J. Thomas, T. Gemming: “Analytical TEM – an Introduction for Operators”.- 9. Let us use the analytical possibilities.- Analytical signals by inelastic interaction.- Emission of X-rays.- Electron energy losses.- Energy dispersive spectroscopy of characteristic X-rays (“EDXS“).- X-ray spectrometers and spectra.- Qualitative interpretation of X-ray spectra.- Quantifying X-ray spectra.- Line profiles and elemental mappings.- Electron energy loss spectroscopy (“EELS“).- Electron energy spectrometer.- Low-loss und Core-loss regions of the spectra.- Qualitative elemental analysis.- Background and multiple scattering: Requirements to the sample.- Measurement of the specimen thickness.- Edge fine structure: Bonding analysis.- Quantifying energy loss spectra.- Energy filtered imaging.- Comparison between EDXS and EELS.- 10. Basics explained in more detail (with a bit more mathematics).- Diffraction at an edge (Huygens’ principle).- Wave function for electrons.- Electron wavelength relativistically calculated.- Electron beam paths in rotational-symmetric magnetic fields.- Resolution limit considering spherical aberration.- Schottky effect.- Electrical potential in rotational-symmetric arrangements of electrodes.- Laue equations and reciprocal lattice, Ewald construction.- Kinematical model: Lattice factor and structure factor.- Debye scattering.- Electrons within the field of a central force.- Mean free path for elastic scattering.- Distances in Moiré patterns.- Contrast transfer function.- Scherzer focus.- Delocalisation.- Potential in electrostatic multipoles.- Electron probe and aberrations.- Classical inelastic collision.- Efficiency of energy dispersive X-ray detectors.- Calculation of Cliff-Lorimer k-factors.- Correction of absorption for EDXS.- Prisms for electrons.- Convolution of functions.- Summary and outlook.- Physical constants.- Hints for further reading.- Index.

 

O autorze

Jürgen Thomas (born in 1948) studied physics at the TU Dresden from 1966 to 1971. In 1970 he had the first contact with electron microscopy and received finally his diploma and doctoral degree on topics of electron microscopy and electron-solid-interactions under supervision of Prof. Alfred Recknagel in Dresden. Between 1978 and 1989 he was responsible for the development of technologies for electron-beam welding and vacuum drying in the industrial research. In 1990 he went back to the electron microscopy and joined the Leibniz Institute for Solid State and Materials Research (IFW) Dresden where he has been working in the laboratory for analytical transmission electron microscopy until today.

Thomas Gemming (born in 1969) studied physics at the University Karlsruhe from 1988 to 1994. He received his doctoral degree on high-resolution transmission electron microscopy in the group of Prof. Manfred Rühle at the Max-Planck-Institut für Metallforschung in Stuttgart in 1998. Afterwards he expanded his field of work to analytical transmission electron microscopy. In 2000 he moved to the Leibniz Institute for Solid State and Materials Research (IFW Dresden) where he is currently working as a department head for Micro- and Nanostructures. Additionally he is currently the executive secretary of the German Society for Electron Microscopy (DGE).

Blurb

This work is based on experiences acquired by the authors regarding often asked questions and problems during manifold education of beginners in analytical transmission electron microscopy. These experiences are summarised illustratively in this textbook. Explanations based on simple models and hints for the practical work are the focal points.

This practically- oriented textbook represents a clear and comprehensible introduction for all persons who want to use a transmission electron microscope in practice but who are not specially qualified electron microscopists up to now.